3701
Energy Efficient Grinding with High Powered Gearless Mills
M. van de Vijfeijken
ABB Switzerland Ltd
G. Barthold
FLSmidth
ABSTRACT: In a standard minerals processing concentrator, the grinding circuit accounts for the vast majority
of the plant’s electrical demand. With the growing need for efficient use of power and large throughput capacities
to treat challenging ore bodies with low head grades, Gearless Mill Drives (GMDs) are rising to the forefront of
mill drive technologies as a means to reduce overall power consumption over the life of the mine, while providing
full operational flexibility and achieving high overall availability. This paper highlights the sustainability benefits
resulting from the optimization of grinding circuits and implementation of fewer large grinding mills with high
efficiency Gearless Mill Drives (GMDs), compared to a larger quantity of smaller grinding mills.
Keywords: Grinding Mills, Gearless Mill Drives, GMD, Mill Selection, Higher Operational Availability,
Increased Operational Efficiency, Variable Speed, Reduced Grinding Footprint, Sustainability, Carbon Footprint
INTRODUCTION
Operating at the heart of a minerals processing concentra-
tor, the grinding circuit design and mill selection requires
careful review to meet the sustainability demands of mines
of the future. This critical stage in the liberation of hard
rock minerals contributes to the vast majority of the elec-
trical demand for the complete minerals processing con-
centrator. As such, along with the grinding mill selection,
the mill drive technology utilized greatly impacts the car-
bon footprint of the mine over the many years of opera-
tion planned for most concentrators. Many plant designers
and operators recognize the need to include variable speed
capability in the selection of the mill drive technology as
this inclusion is the first step in allowing for maximum
process and operational optimization. With the inherent
inclusion of variable speed capability, the prominent avail-
able drive technologies for large grinding mills are geared
mills with low-speed synchronous motors or gearless mills
with wrap-around motors or Gearless Mill Drives (GMDs).
Over the past 4 decades, the size of horizontal tumbling
mills increased immensely and concentrators with an enor-
mous quantity of small mills are not being built anymore
instead, simplified process lines with a truly minimized
number of large mills are being preferred, as stated by Lane
(2017): “Machine capacity increases have led to simpler cir-
cuits (fewer parallel process lines) that are easier and safer
to maintain.” These are the technologies considered in the
enclosed mill size, quantity, and technology trade-off which
have been conducted for a typical copper concentrator
treating competent ore. An emphasis on carbon footprint
for the varying mill sizes and drive technologies has been
targeted to determine the impact of this selection over the
life of mine. Carbon footprint data has been analyzed with
a focus on overall energy efficiency and how this translates
to CO2 emissions.
Energy Efficient Grinding with High Powered Gearless Mills
M. van de Vijfeijken
ABB Switzerland Ltd
G. Barthold
FLSmidth
ABSTRACT: In a standard minerals processing concentrator, the grinding circuit accounts for the vast majority
of the plant’s electrical demand. With the growing need for efficient use of power and large throughput capacities
to treat challenging ore bodies with low head grades, Gearless Mill Drives (GMDs) are rising to the forefront of
mill drive technologies as a means to reduce overall power consumption over the life of the mine, while providing
full operational flexibility and achieving high overall availability. This paper highlights the sustainability benefits
resulting from the optimization of grinding circuits and implementation of fewer large grinding mills with high
efficiency Gearless Mill Drives (GMDs), compared to a larger quantity of smaller grinding mills.
Keywords: Grinding Mills, Gearless Mill Drives, GMD, Mill Selection, Higher Operational Availability,
Increased Operational Efficiency, Variable Speed, Reduced Grinding Footprint, Sustainability, Carbon Footprint
INTRODUCTION
Operating at the heart of a minerals processing concentra-
tor, the grinding circuit design and mill selection requires
careful review to meet the sustainability demands of mines
of the future. This critical stage in the liberation of hard
rock minerals contributes to the vast majority of the elec-
trical demand for the complete minerals processing con-
centrator. As such, along with the grinding mill selection,
the mill drive technology utilized greatly impacts the car-
bon footprint of the mine over the many years of opera-
tion planned for most concentrators. Many plant designers
and operators recognize the need to include variable speed
capability in the selection of the mill drive technology as
this inclusion is the first step in allowing for maximum
process and operational optimization. With the inherent
inclusion of variable speed capability, the prominent avail-
able drive technologies for large grinding mills are geared
mills with low-speed synchronous motors or gearless mills
with wrap-around motors or Gearless Mill Drives (GMDs).
Over the past 4 decades, the size of horizontal tumbling
mills increased immensely and concentrators with an enor-
mous quantity of small mills are not being built anymore
instead, simplified process lines with a truly minimized
number of large mills are being preferred, as stated by Lane
(2017): “Machine capacity increases have led to simpler cir-
cuits (fewer parallel process lines) that are easier and safer
to maintain.” These are the technologies considered in the
enclosed mill size, quantity, and technology trade-off which
have been conducted for a typical copper concentrator
treating competent ore. An emphasis on carbon footprint
for the varying mill sizes and drive technologies has been
targeted to determine the impact of this selection over the
life of mine. Carbon footprint data has been analyzed with
a focus on overall energy efficiency and how this translates
to CO2 emissions.